The invention relates to an apparatus for opening pressed fiber bales of spinning material, e.g. cotton, synthetic fibers or the like, by means of a milling roller whose toothed disks act on the bale surface through a grid formed of bars. The outwardly directed teeth of the toothed disk are directed oppositely to the adjacent tooth extending in outward direction.
In an opening means of the above mentioned type, known from German Patent No. 23 52 478, the teeth of the opening disk are individual projections arranged symmetrically to its longitudinal axis. The side edge of the free end of each tooth as an angular, preferably a pointed angular design, and it is possible for each tooth to be directed outwardly in the opposite direction to the adjacent tooth. The teeth of such an opening disk used for milling are effective in each direction of rotation of the disk and in each direction of movement of the fiber bale. The opening disks are arranged in pairs between two grid rods. The opening disks are set relatively close together, side by side, within a space determined by the grid bars. Further, the height of the teeth of the disk is rather short.
German Patent No. 11 31 567 discloses a bale rasp for opening pressed fiber bales in which the saw toothed disks are provided between the grid rods and are tumbling, i.e. they are arranged at an angle different from ninety degrees relative to the axis of rotation. By this means, it is intended that due to their oblique position, the disks tumble to and fro between two extreme positions thus sweeping over nearly the total space between the grid rods. The bales are reduced in the total zone situated between the grid rods. The teeth of the rasp disks are situated in the slope of the tumbling plate. A teeth setting is not realized this way. Further, the height of the teeth is extremely short so that the fiber material is mainly reduced by a rasping operation rather than by milling.
The known opening means do not maximize and optimize the careful reduction of fibers from pressed bales, but the fibers are torn out of the bale as flocks of lesser or larger size, whereby, due to damaged fibers, the amount of short fibers is increased.